Field of the Invention
The invention relates to a filter plug having a plug body being made of insulating material and a number of parallel plug pins being disposed in a set pattern and being surrounded by the plug body.
Such filter plugs are used, on one hand, to provide a plug-in electrical connection and, on the other hand, to block out interference which could be transmitted through that connection. The plugs are usually soldered onto a printed circuit board on which there is a circuit and project through an opening in a housing surrounding the circuit.
In order efficiently to block out interference which is fed into the housing through the contact pins, or interfering radiation which can be radiated onto the contact pins from the circuit, filter elements made of ferrite material are fitted onto the filter plugs, as in German Utility Model DE-U 91 12 098, corresponding to U.S. Pat. No. 5,370,555. The filter elements have bores matching the pattern of the plug pins and they are held in the plug by the contact pins.
Since the plug connector is made of an insulating material, the interfering radiation can enter and leave unimpaired. In order to block out the interfering radiation effectively, relatively large filter elements or screening plates that surround the plug are necessary.